1. Technical Field
The invention is in the field of handling of time-sensitive data over packet switched networks, and more particularly transmitting and receiving video data over the Internet.
The invention relates to a method of providing a streaming video service to a client across a packet network whilst reducing the start-up delay usually associated with preparing a buffer of data while maintaining the use of a buffer. The invention also relates to a method of controlling the transmission rate of the streaming video to adapt to congestion in the network.
2. Related Art
Traditionally the Internet has supported traffic such as FTP, e-mail and web-surfing, where the overall delay does not intrinsically detract from the final presentation of the media. The advent of faster processing multimedia PC's has driven the delivery of multimedia, including video, over the Internet. Time-sensitive applications however require continuous, quality of service guaranteed, high bandwidth data channels, which is seemingly at odds with the packet-based nature of the Internet and has the potential to disrupt transmissions with unacceptable packet jitter, i.e. the variation in the inter-arrival times of packets caused by variable routing and changeability of delivery rates owing to congestion. Currently, commercial streaming technologies overcome jitter by constructing a large buffer (5-30 seconds) before starting to playback video material. This start-up delay is non-optimal for a user, who may have to wait for this period, before realizing that the content requested is incorrect; and generally detracts from the users experience of the multimedia presentation.